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Fishmeal cargo loading and associated problem of self heating
Fish meal, or fishmeal, is a commercial product made from fish and the bones and offal from processed fish.
It is a brown powder or cake obtained by drying the fish or fish trimmings, often after cooking, and then grinding it.
If it is a fatty fish it is also pressed to extract most of the fish oil

Fishmeal is a nutrient-rich and high-protein supplement feed ingredient that stores well,
and is used primarily in diets for domestic animals and sometimes as a high-quality organic fertilizer.

The original fishmeal trade involved products now falling into the Class 4.2
category. The basic requirements for the carriage of cargo of this type were
that it was bagged and aged for a period of not less than 28 days between
production and loading on the carrying ship.

Stowage was by the double
strip stow method, that is, the bags were stowed longitudinally in the cargo
spaces with transverse channels every two bags. Cargo stowed in this way
was to be ventilated throughout a voyage, weather permitting. There were
also requirements in terms of maximum oil content, maximum and minimum
moisture contents and temperature at the time of loading. Strict adherence
to these conditions permitted generally uneventful carriage of fishmeal
over protracted voyages. It will be appreciated, however, that the stowage
requirements resulted in a high stowage factor and were expensive in both
labour and materials (dunnage).

It has been known for many years that heating of fishmeal to the point of
fire is due to aerial oxidation of reactive chemical sites on fish oil
molecules. All oxidation reactions are associated with the product of heat.
Thus, the rationale behind the practice discussed briefly above was that
the most reactive material was oxidised during the aging process and the
residual oxidisable material reacted with atmospheric oxygen at a rate at
which the heat produced could be removed by ventilating air under the
conditions of stowage stipulated. It followed that if some procedure could
be found which would either eliminate or drastically reduce the rate of
oxidation it would be possible to carry oily fishmeal products as bulk cargo,
or as bagged cargo in block stow.

Certain shipowners approached the problem by the use
of inert gas. Special ships were built which were
equipped with onboard inert gas producing equipment,
similar to that used on tankers, and had hatchcover
systems which were substantially airtight. This system
works satisfactorily provided the number of loading and
discharging ports served on a single voyage is limited.
It will be appreciated that each time a hatchcover is
opened the inert atmosphere is replaced by air and the
inerting operation must be repeated again when the
hatches are closed.

The fishmeal industry sought to resolve the problem by
modifying the product to render it inert or less
susceptible to oxidation. This was achieved by the
addition of antioxidant during the production of the
meal. Fishmeal suitably treated with antioxidant was
included under Class 9 (Miscellaneous Dangerous
Substances ) in the IMDG Code. Antioxidant-treated
oily fishmeal, conforming to the requirements of the
Code, can be carried either as a bulk cargo or in bags
in block stow. This permitted relaxation of both stowage
and ventilation requirements during ocean carriage.
Introduction of antioxidant-treated fishmeal on a large
scale roughly coincided with drastic fall in the annual
production of fishmeal on the west coast of South
America. However, sufficient cargo was shipped for it
to be apparent that the process could give a stable
product for carriage in bulk or block stow.

In 1982 there was a series of incidents involving
serious heating, sometimes to the point of fire, in
fishmeal cargoes shipped from Chile on various long
ocean voyages.Some facts of
general interest have emerged during investigations.
Fishmeal is produced by cooking the fish and
extracting oil and aqueous fluids mechanically. The
cake which is produced is then dried and milled. The
milled meal is cooled and treated with antioxidant
(ethoxyquin), usually by spraying the meal as it passes
through a trough.

As indicated earlier, heating of fishmeal is due to
atmospheric oxidation. The chemical process is
complex and involves a series of reactions. The amount
of heat produced by these reactions varies. The
reactions producing most energy are those towards the
end of the series. Antioxidant stops the reaction chain
before these later reactions can occur.

Antioxidant is used up as treated fishmeal ages. If an
insufficient quantity is added at the time of production,
it will be used up before the condition of the fishmeal
has been stabilised. As a result, at some stage after
production, oxidation will start, producing substantial
quantities of heat and the risk of a serious rise in
temperature in the affected meal. However, this will
not be evident for some time after loading. This was the
case in shipments from both Chile and Peru mentioned
earlier in this article.

When serious heating occurs, this can result in
carbonisation and/or fire. Many small isolated pockets
of bags may be involved. During investigations, these
pockets were found in regions of maximum ventilation
and also in the interiors of large block stows. It follows
that the primary cause was the intrinsic reactivity of
the contents of a few bags rather than unsuitable
stowage or ventilation.

Bagged fishmeal

Bagged fishmeal presents the majority of problems.

Documentation

The master should have onboard a copy of the latest
IMDG Code. Entries for fishmeal are on
pages 58, UN No.1374 for unstabilised fishmeal and
pages 103, UN No. 2216 for stabilised (i.e. anti-oxidant
treated) fishmeal. He should also have a copy of the
IMO Code of Safe Practice for Solid Bulk Cargoes
(IMSBC Code) latest edition, where the entry for
stabilized fishmeal can be found at pages .

The master must ensure that he obtains and retains
certificates for antioxidant treated fishmeal as required
by the Code, covering all the cargo loaded; that these
certificates give all the information required; and
figures given conform with the requirements set out in
the special provisions at page 189, Section No 907,
Volume 2 of the Code.

Since de-regulation of the fishmeal trade in Peru,
certificates may be issued by a person or company
recognized by the Government of Peru, the competent
authority. Certificates for Chilean fishmeal, which very
rarely gives problems, are issued by IFOP.

Action to be taken by the ship or surveyors
acting for the ship during loading

The temperature of the contents of as many bags as
possible should be measured. Where these do not
comply with the requirements under special provision
300, page 188 of the Code, the relevant bags must be
rejected. If high temperatures are being observed it
may be necessary to stop the loading of the relevant
parcel to allow more extensive temperature checking.
Any wet or water-stained or caked bags should be
rejected. It must be appreciated that fishmeal cargoes
packed in black woven polypropylene bags with
staining are not readily detectable. Thus again it may
be necessary when such staining is observed that
loading of the relevant parcel is suspended or slowed
to allow a proper examination. Torn bags should also be
rejected.

Stowage

Standard stowage practice for bagged cargoes should
be adopted, i.e. use of double dunnage on decks and
tank tops and provision of a spar ceiling or adequate
dunnage to prevent the cargo coming into contact with
the ship’s sides, pipes and bulkheads especially those
which are liable to become heated.

Details of stowage precautions for fishmeal can be
found at pages of
Volume 1 of the 2009 edition of the IMDG Code. For
UN 1374 fishmeal, where loose bags are carried,
double strip stowage is recommended, provided there
is good surface and through ventilation.

For UN 2216
fishmeal,where loose bags are carried, no special
ventilation is required for block stowages – IMDG
Code, Volume 2, page 103. Flammable materials such
as paint should be removed from storerooms
immediately above or adjacent to cargo spaces loaded
with bagged fishmeal.

Installation and operation of temperature
sensors

The IMO requires that the temperature of cargo in each
hold is monitored. This can only be satisfactorily
performed by installation of remote reading sensors.
The Committee specially recommends that installation
is not performed by the ship’s crew as they should be
solely engaged observing loading operations.

The BC Code requires that the temperature of cargo in
each hold is monitored throughout the voyage. This can
only be satisfactorily performed by the installation of
remote reading sensors which are normally connected
to a switch box which also has a connection for a readout
meter. The installation is normally carried out by a
specialist survey organisation who are employed by the
shippers or charterers. The Committee specifically
recommends that installation is not performed by the
ship’s crew as they should be solely engaged observing
loading operations. It is common to install sensors at
two or three levels in a lower hold and one or two levels
in a tween deck depending on the depths of the
relevant spaces. Between four and eight sensors are
distributed at each level depending on the cross
sectional area of the cargo spaces.

The master should obtain a drawing from the
installation operator indicating the locations of sensors
in each cargo space. At completion of loading, for
preference, but in any event when all sensors have
been installed, the master or chief officer should check
the temperature as indicated by each sensor in the
presence of the installing operator. This will ensure that
the ship’s command is conversant with the equipment.
It will also show whether each sensor is functioning
correctly.

Abnormally high or low figures will
indicate malfunction from the outset of the voyage. At
this stage it is impractical to replace sensors and such
an operation should not be attempted. The installing
operator should be asked to sign the entry covering the
first set of recordings which should be entered, as
read, in a bound book. Subsequently, the figures for
each sensor should be read and recorded in the book
each watch for the first few days of the voyage. If they
are more or less stable they may subsequently be read
at eight-hourly intervals as required under Special
requirements (2) in the BC Code entry. If some
temperatures in a space start to rise, temperature
reading should revert to four-hourly intervals for all
sensors in the space.

From experience, it is known that there can be some
increase in temperature (possibly up to 34°C) as
recorded from some sensors, at the outset of a voyage
after which the temperature stabilises. This situation
need not give rise to concern.

If, however, the
temperature of one or more sensors exceeds 40°C and
continues to rise, the master should take timely steps
to seal the relevant hatchcovers using sealing tape
and if necessary plastic or foam sealant or cement.

Consideration should be given at this stage to sealing
ventilation openings; owners and charterers should be
informed of the temperature figures and their advice /
instructions sought. Members of the Committee are on
occasions requested to advise owners or charterers
when this situation arises and advice is normally given
on the temperature trends over a time period. Hence
when a master is forwarding information he should
ensure it is clear and the temperature figures for each
cargo space are always reported in the same
sequence.

In any event, the instructions in the BC Code entry
Special requirements (3) should be followed, i.e. if any
temperature sensors indicate a cargo temperature in
excess of 55°C, the cargo space and any
interconnecting cargo space should be sealed
effectively and ventilation restricted. If self-heating
continues, then CO2 or inert gas should be injected as
stipulated in the fire fighting manual provided by the
installers of the system. The injection should take place
slowly over a 24-hour period. It is basically undesirable
to inject less gas than is recommended in the manual,
even though this means that only a few cargo spaces
can be so treated.

It should be appreciated that any cargo heating results
from an oxidation process. This means that the oxygen
concentration in a hold is depleted and the
concentration of nitrogen (an inert gas) increases.
Hence, in a sealed hold, cargo heating tends to be selfquenching.
It is therefore of paramount importance
that the master has all necessary materials onboard to
allow very efficient sealing of cargo spaces in order
to minimise atmospheric interchange. Very efficient
sealing may be a time-consuming operation, but should
never be skimped.

Technically, provided that hold sealing is adequate, it
would be possible for a ship with cargo heating in all
her holds, to sail safely across the Pacific Ocean with
her CO2
supply exhausted (assuming a sufficient
reserve for the engine room). However, such action
would only be recommended if sealing efficiency could
be guaranteed. Under normal circumstances, where
there is obvious progressive heating, a ship would be
recommended to go to a port of refuge to obtain
adequate CO2 supplies. This often involves fitting a
bulk tank containing several tonnes of CO2
.

If
considered necessary, further sealing should be
performed whilst the ship remains in port.
Unless special circumstances prevail, sealed
hatchcovers should not be opened until the first
discharge port for that hold is reached. An accurate
assessment of the situation in any cargo space can be
obtained by measuring the oxygen concentration via a
pipe connected to an oxygen meter which is introduced
ideally via dedicated points of access or alternatively
by slightly opening an access manhole. The manhole
should be closed and secured immediately after
measurements have been taken.

Although some ships
have oxygen meters onboard and have crew
conversant with their use, it is generally recommended
that, where possible, measurements of oxygen levels
are made by surveyors. If they are made by the ship,
the instrument should be checked immediately before
use by checking the oxygen concentration of the
external atmosphere (20.8%). When oxygen levels are
below 10% heating is greatly restricted. Even without
use of CO2, this situation may be achieved in a few
days where hatches are effectively sealed and there is
a substantial quantity of cargo heating in a hold.

Discharge fishmeal

Heating cargoes (if any) should be discharged first.
However, where this is not practicable, the rate of
spread of heating in a cargo space can drastically be
reduced by maintaining a low oxygen concentration.
This is done for preference by the use of CO2
or when
supplies are not available by keeping the holds
sealed.

It must be appreciated, however, that once the
holds are opened for discharge and the oxygen
concentration is allowed to rise to at least 20%, which
is necessary for safe working in the hold, heating will
resume at an accelerating rate. Hence attempts should
be made to discharge pockets of heating cargo as soon
as possible. On some occasions this can be achieved
without difficulty. However, on occasions smoke
generation becomes excessive, preventing manual
operations. There are then several options for dealing
with this problem and the choice depends on the
circumstances prevailing.

The first option is to reseal the hold and inject CO2, the
minimum quantity injected being that recommended by
the installers of the ship’s CO2 system. Again this
operation should take place over a 24-hour period. The
hold should then be left sealed for at least four days.

The oxygen concentration must again be allowed to
rise to 20% before labour is allowed into the space to
resume discharge. This option, when successful,
results in the minimum amount of cargo damage but
extends the discharging period. It may be considered
impractical if it has to be repeated several times.
The second option is to control smoke evolution by the
use of water sprayed through a fine spray directly onto
the smoking cargo, whilst discharge proceeds. This
procedure, if properly used, results in limited water
damage to part of the cargo. However, excessive water
is often applied, particularly when the local fire service
intervenes, and the amount of cargo wetted can be
substantial.

Very occasionally, the cargo will actually ignite. Flames
should be extinguished with a water spray.
The third and last option which should only be used
when other methods have failed is to use a water spray
to control smoke evolution or fire and discharge
heating pockets by grab. The procedure obviously
results in more cargo damage.

Members of the Committee have had experience of
fires in fishmeal igniting flammable cargo in adjacent
spaces with disastrous results. Hence the earlier
advice that flammable materials should not be stored in
storerooms adjacent to or above holds loaded with
fishmeal.

Damaged and apparently sound cargo should always
be separated at the time of discharge. However,
even badly heated cargo has feed value and can be
incorporated in cattle feed. Hence, cargo should never
be left onboard to be dumped at sea.

Bagged fishmeal carried in containers

Bagged stabilised (i.e. UN 2216, Class 9) fishmeal may
be carried in freight containers as indicated in Volume 1
of the IMDG Code at page 322. It is probable that
containers will be delivered alongside already sealed.
However, if the master is in a position to see the
containers being stuffed he should ensure they are
clean and that the maximum quantity of bags are
placed in each container.

In any event he should
ensure that the container doors and other openings are
properly tape-sealed to minimise possible air ingress.
On the voyage, the temperature of the outsides of
containers, if stowed in accessible positions should, if
possible, be checked regularly by feeling them (in any
event, as indicated in Volume 1 of the IMDG Code at
page 322, 7.1.10.3.2.2 “Temperature readings in the
hold should be taken once a day early in the morning
during the voyage and recorded”.

If any container
becomes hot they should be cooled using water;
“...consequent risk to the stability of the ship should be
considered.” 7.1.10.3.2.3. If smoke is seen issuing
from a container, a hole should be punched in the side
at the top of the container, a hose nozzle fitted and
the container flooded.
It is self-evident that masters must ensure there is
reasonable access to any containers stowed under
deck.